The recent, marked increase in ice discharge from many of Greenland’slargeoutlet glaciers has upended the conventional view that variationsin ice-sheet mass balance are dominated on short time scalesby variations in surface balance, rather than ice dynamics.Beginning in the late 1990s and continuing through the pastseveral years, the ice-flow speed of many tidewater outlet glacierssouth of 72° North increased by up to 100%, increasing theice sheet’s contribution to sea-level rise by more than 0.25mm/year. The synchronous and multiregional scale of thischange and the recent increase in Arctic air and ocean temperaturessuggest that these changes are linked to climate warming.

The article’s key conclusion about Kangerlussuaq (KL) — based on a study of ice dynamics from 2000 to 2006 — hardly justifies labeling it an “inconveniently growing” glacier:

From summer 2004 to spring 2005, KL retreated by 5 km, andits speed increased by 80% near the front and by 20% at 30 kminland. Between April and July 2005, the increase inspeed migrated rapidly inland with a 5% decrease in speed closeto the front and a 7% increase in speed in areas farther inland(up-glacier). This upstream propagation continued from July2005 through July 2006, with the near-front deceleration of15% and up-glacier acceleration of 25%, with the transitionbetween speedup and slowdown at 15 km. The glacier thinned rapidlyduring acceleration, with 80 m of thinning near the front andthinning of at least 40 m extending 40 km inland by summer 2005.Thinning moved inland between 2005 and 2006, with a peak thinningof 68 m at about 26 km, but with virtually no thinning at thefront. Average thinning over the glacier during the summer of2006 declined to near zero, with some apparent thickening inareas on the main trunk.

The authors conclude: “Integrating the time series of discharge anomaly from 2000 to2006 gives totals of 52 Gt at KL.” That is, 52 billion tons of ice loss! And apparently most of the loss from KL and another glacier came “in the interval from summer 2004 to summer 2006.”

[O]ur results are notablein that they show that Greenland mass balance can fluctuaterapidly. If these changes are the result of recent warm summers, continued warming may cause a long-term drawdown of theice sheet through a series of such discharge anomalies, perhapswith a similar degree of variability.

Are you reassured? Greenland can discharge ice very rapidly, and is likely to do so in the future, especially if we take no action to reduce global warming.

If Lomborg actually read this article, he should be ashamed of citing its research to convince people that they don’t have to worry about sea level rise.

Finally, Lomborg believes in polling (economic) experts to help guide the public — that is the basis of his Copenhagen Consensus. Well, the experts are very worried about one meter sea level rise over the next century or so. As the AP recently reported:

Lomborg is very familiar with the climate literature, as his writing makes clear — and I suppose that’s what bugs me the most. He cherry-picks and selectively cites, when any objective review of the literature and discussion with the experts would be lead one to be more worried about the climate, not less.

I had to look up this Lomborg thing for something lately, and in fact there is no Kangerlussuaq glacier; the KL refers to the Kangerdlugssuaq glacier on eastern Greenland, whereas Kangerlussuaq is on the west side of Greenland where there is an airport, near Sondre Stromfjord. Visitors fly in there on their way to go to see the Jakobshavn Glacier, further north on the west.